Venlafaxine (Effexor XR)

1. Health Canada Product Monograph — Venlafaxine

• Venlafaxine treats major depressive disorder.
• Venlafaxine treats generalized anxiety disorder causing significant distress.
• Venlafaxine treats social anxiety disorder (social phobia).
• Venlafaxine treats panic disorder, with or without agoraphobia.

• There are no adequate, well-controlled studies of venlafaxine in pregnant women; it should be used during pregnancy only if clearly needed.
• Babies exposed to venlafaxine or similar antidepressants late in the third trimester can develop complications at birth, including breathing difficulty, bluish skin color, feeding problems, seizures, temperature instability, and constant crying, sometimes requiring hospitalization.
• Using venlafaxine in mid-to-late pregnancy may increase the risk of preeclampsia, and use near delivery may increase the risk of heavy bleeding after childbirth.
• If venlafaxine needs to be stopped during pregnancy, the dose should be reduced gradually rather than stopped abruptly.

• Venlafaxine and its active metabolite pass into breast milk, so breastfeeding is not recommended while taking this medication.

• Older adults do not need routine dose adjustment based on age alone, but caution is advised since some older individuals may be more sensitive to its effects.
• Older adults may be at greater risk of a sodium imbalance (hyponatremia) and of falls or fractures associated with dizziness.

• Venlafaxine is not approved for use in patients under 18 years of age.

• For major depressive disorder, the usual starting dose is 75 mg once daily with food; some patients may start at 37.5 mg per day for the first 4 to 7 days, with increases of up to 75 mg per day at intervals of about 2 weeks, up to a maximum of 225 mg per day.
• For generalized anxiety disorder, treatment starts at 37.5 mg once daily for 4 to 7 days, then increases to a usual dose of 75 mg once daily, up to a maximum of 225 mg per day.
• For social anxiety disorder, the usual dose is 75 mg once daily, with a maximum of 225 mg per day.
• For panic disorder, treatment starts at 37.5 mg once daily for 7 days, then increases to a usual dose of 75 mg once daily, up to a maximum of 225 mg per day.
• Patients with mild to moderate liver impairment should have their total daily dose reduced by about half, with further individualization since clearance varies widely.
• Patients with reduced kidney function should have their total daily dose reduced by 25-50%; patients on hemodialysis need a 50% dose reduction and should withhold the dose until dialysis is finished.
• When discontinuing venlafaxine after more than a week of use, the dose should be tapered gradually rather than stopped abruptly to reduce the risk of discontinuation symptoms; tapering over at least two weeks is recommended after more than six weeks of use.
• If a dose is missed, it should be skipped rather than doubled up at the next scheduled time.

If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.

• Reported symptoms of venlafaxine overdose include a fast heart rate, changes in consciousness ranging from drowsiness to coma, dilated pupils, seizures, and vomiting.
• Other reported effects include ECG changes such as QT interval prolongation and widened QRS complex, abnormal heart rhythms, low or high heart rate, low blood pressure, muscle breakdown (rhabdomyolysis), liver damage, and serotonin syndrome.
• Fatal overdoses have been reported with venlafaxine alone, including at doses only several times the usual therapeutic dose.
• There is no specific antidote; treatment involves maintaining the airway, oxygenation, and ventilation, monitoring cardiac rhythm and vital signs, and general supportive care.
• Activated charcoal should be given; inducing vomiting is not recommended, and dialysis or forced diuresis are unlikely to help due to venlafaxine's large volume of distribution.

• Nausea may occur.
• Dry mouth may occur.
• Drowsiness (somnolence) may occur.
• Dizziness may occur.
• Trouble sleeping (insomnia) may occur.
• Nervousness may occur.
• Sweating may occur.
• Constipation may occur.
• Loss of appetite may occur.
• Tremor may occur.
• Abnormal or vivid dreams may occur.
• Blurred or abnormal vision may occur.
• Sexual side effects, including abnormal ejaculation, orgasm difficulty, or impotence, may occur in men.
• Headache may occur.
• Weakness (asthenia) may occur.
• Yawning may occur.

Serious side effects require immediate discussion with the prescriber or emergency care.

• All antidepressants, including venlafaxine, carry an increased risk of suicidal thoughts and behaviour, particularly in the early weeks of treatment or after a dose change; close monitoring is needed.
• Sustained increases in blood pressure can occur and should be monitored, especially at higher doses.
• Serotonin syndrome, a potentially life-threatening reaction with symptoms such as agitation, rapid heartbeat, high body temperature, muscle rigidity, and coordination problems, can occur, especially when combined with other serotonergic drugs.
• Neuroleptic malignant syndrome-like reactions, with high fever, muscle rigidity, and altered mental status, have rarely been reported.
• Seizures can occur and require prompt discontinuation of the medication.
• Abnormal bleeding, including gastrointestinal bleeding and bruising, can occur, especially when combined with NSAIDs, aspirin, or blood thinners.
• QT interval prolongation and, rarely, dangerous heart rhythm disturbances such as torsades de pointes have been reported.
• Severe allergic skin reactions, including toxic epidermal necrolysis and Stevens-Johnson syndrome, have been reported.
• Discontinuation symptoms, including dizziness, sensory disturbances, agitation, and anxiety, can occur if the medication is stopped abruptly.
• Angle-closure glaucoma has been reported.
• Seek urgent medical attention for chest pain, a severe headache with vision changes, muscle rigidity with high fever, signs of unusual bleeding, or thoughts of self-harm.

• Use with caution in patients with high blood pressure, and monitor blood pressure regularly during treatment.
• Use with caution in patients with heart disease or a family history of QT prolongation.
• Use with caution in patients with a history of seizures.
• Use with caution in patients with a history of bleeding disorders or those taking blood thinners, NSAIDs, or aspirin.
• Use with caution in patients with a history of glaucoma or increased eye pressure.
• Use with caution in patients with liver or kidney impairment, and adjust the dose accordingly.
• Use with caution in patients with a history of drug abuse, and monitor for signs of misuse.
• Use with caution when driving or operating machinery until the effects of the medication are known.

• Contraindicated in patients hypersensitive to venlafaxine or any ingredient in the product.
• Contraindicated in patients taking, or within 14 days of stopping, a monoamine oxidase inhibitor (MAOI), due to the risk of serious or fatal reactions.

• Combining venlafaxine with an MAOI, or starting either within 14 days of stopping the other, is contraindicated due to the risk of serotonin syndrome and other serious reactions.
• Combining venlafaxine with other serotonergic drugs, such as SSRIs, other SNRIs, triptans, lithium, tramadol, fentanyl, or St. John's wort, increases the risk of serotonin syndrome.
• Combining venlafaxine with drugs that prolong the QT interval, such as certain antiarrhythmics, antipsychotics, and macrolide antibiotics, may add to the risk of heart rhythm disturbances.
• Combining venlafaxine with warfarin, NSAIDs, or aspirin can increase the risk of bleeding.
• Strong CYP2D6 or CYP3A4 inhibitors can raise venlafaxine blood levels; combined inhibition of both pathways is not recommended.
• Ketoconazole increases blood levels of venlafaxine and its active metabolite, particularly in patients who metabolize CYP2D6 poorly.
• Venlafaxine can raise metoprolol blood levels.
• Venlafaxine can increase risperidone blood levels through CYP2D6 inhibition, though this does not require a dose change.
• Venlafaxine can decrease indinavir blood levels.
• Elevated clozapine levels and related adverse events have been reported when venlafaxine was added to clozapine therapy.
• Alcohol should be avoided, as it can add to psychomotor impairment and increase the danger of overdose.

• Effexor XR should be taken with food; food does not significantly change how much venlafaxine is absorbed, but taking it with food is the recommended, consistent way to take each dose.

• Take Effexor XR once daily with food, either in the morning or in the evening, swallowing the capsule whole without crushing, chewing, or dividing it.

• Store venlafaxine extended-release capsules at room temperature (15-30°C) in a dry place.

• Venlafaxine (Effexor XR) is an antidepressant used for depression, generalized anxiety, social anxiety, and panic disorder.
• Take it with food at the same time each day, and never stop it suddenly; your doctor will help you taper off gradually if treatment needs to end.
• It can take several weeks of treatment to feel the full benefit; contact your doctor if you notice worsening mood, agitation, or thoughts of self-harm, especially early in treatment.
• Avoid alcohol and tell every healthcare provider you see that you take this medication, since it interacts with many other drugs.